Spar Question

[Jim Herpst]

Who is making complete ready to go spars for the B series ? Anyone ?

Who has the bushings for the 85 install ?

[Acroeric]

Re: Spar Question

I made my own and also cut down my own bushing stock. Pretty simply to do actually. I made a drilling jig for the compression struts, aileron hinges, and wing attach fittings. You are welcome to use it. You will also need a good precision planer and a joiner that is more than 6" wide. Spruce is a little tricky to feed into the joiner without splintering a bit.

[Jim Herpst]

Re: Spar Question

good deal thanks Eric. A friend asked me today over lunch. If there aint any available then cottage industry rules!! I may ask to borrow your jig.
Thanks ! JIM

ps: said it befor say it again ...what a great group here !! We have the best Airplane and the best folk to boot !!!!

[Guest]

Re: Spar Question

When I made mine I had no access to a planer to reduce the spar thickness at the root for the plywood . And I am not sure I trusted my long awaited spruce to someone I didn't know to shave the ends.

So to shaved the spar but thinner to make room for the plywood reinforcement plates I did this;I purchased an electric hand planer about 2" wide for $100 and made a square angle iron jig to hold it that had a threaded adjustable skid/foot in each corner. The jig was wide enough so that it fit over the spar width enough that the planer could do the full spar width, a little more than 12" wide as I recall. The planer was then supported above the work and I adjusted the legs until in planed parallel to the hard surface flat formica table top material that I bought for this purpose. Table was small, like 2x2 so it was cheap.

I practiced on scrap until I was sure that I could shave off the proper amount across the entire ~6" width with the ~2" planer. Also I set a stop so that it would only travel down the spar lenght a certain amount.

Worked fine. And of course I had to clamp the work to the table.

Dave

[Jim Herpst]

Re: Spar Question

hmm wonder if on the root end one could make the spar cut down to cleanly follow that of the plywood to be attached. If you look at a "factory" spar it is clearly evident to see additional material of the spar cut down beyond the end of the plywood by what looks like a joiner as it rounds off....

[Guest]

Re: Spar Question

I was planing mine in the post above to shave out a space for the plywood at the root, although I never explicitly said that. Sorry

Dave

[Jim Herpst]

Re: Spar Question

No problem. I suppose that answers my question then. If you planed it then you have a tight fit ( smooth from plywood end transition to the spar ) correct?

[Jim Herpst]

Re: Spar Question

Reason I am harping on this is actually Iwould think it better to be planed and NOT have excess material cut beyond the ply....

[Acroeric]

Re: Spar Question

The joiner works really well for this- I used a jig to make the stop and tested it on scrap first to set the depth. I think it took me 10 minutes to set it up and 5 mnutes to do all the spars plus it leaves a good gluing surface.

[Pearson]

Re: Spar Question

I think it was on this forum where I read about someone using a router make the area for the doubler. Seems like the joiner would leave a much smoother surface. I like the idea of haveing a smooth transition from the doubler to spar. Eric, how about some pictures?

[Guest]

Re: Spar Question

Reason I am harping on this is actually Iwould think it better to be planed and NOT have excess material cut beyond the ply....

ahh

I planed it but I planed parallel to the spar so that I did get that curve up an away from the spar.

I think that this is better than having it squared off and the plywood abutted. I think its better because abrupt changes in cross section often lead to cracks.

Dave

[Guest]

Re: Spar Question

I think it was on this forum where I read about someone using a router make the area for the doubler. Seems like the joiner would leave a much smoother surface. I like the idea of haveing a smooth transition from the doubler to spar. Eric, how about some pictures?

Even the Rube Goldberg scheme and electric planer that I used left a very smooth gluing surface.

[Acroeric]

Re: Spar Question

I wish I would have taken some pictures.....I am terrible about just doing things and not taking the time to do that. You guys are right- you want a nice radius between the area that is thinned for the doubler and the transition to full thickness or there is tendency to crack. On several of the clipped wings I have built I just left the spar the same thickness and made new wing attach fittings. I drilled them in the clamped position so I could slide all the ribs in place and then glue the doublers on after the last rib went on. Gotta love the world of experimental aviation!

[Jim Herpst]

Re: Spar Question

Eric ok I will bite How did you MAKE the 85hp bushings ? We can't find them to purchase? If I have to make the damn things I will but would think.......

[crispy critter]

Re: Spar Question

I turn them down by hand on a leathe. Once I get them close with a blade,I switch to a light file. Easy to make but takes a little time.